22,603 research outputs found

    Avaliação do estado nutricional de espécies componentes de sistema agroflorestais em solos de baixa fertilidade em Rondônia.

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    Este trabalho tem como objetivo avaliar o estado nutricional de espécies componentes de sistemas agroflorestais estabelecidos em solos de baixa fertilidade no Estado de Rondônia

    Manipulation of Magnetic Skyrmions by Superconducting Vortices in Ferromagnet-Superconductor Heterostructures

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    Dynamics of magnetic skyrmions in hybrid ferromagnetic films harbors novel physical phenomena and holds promise for technological applications. In this work, we discuss the behavior of magnetic skyrmions when coupled to superconducting vortices in a ferromagnet-superconductor heterostructure. We use numerical simulations and analytic arguments to reveal broader possibilities for manipulating the skyrmion-vortex dynamic correlations in the hybrid system, that are not possible in its separated constituents. We explore the thresholds of particular dynamic phases, and quantify the phase diagram as a function of the relevant material parameters, applied current and induced magnetic torques. Finally, we demonstrate the broad and precise tunability of the skyrmion Hall-angle in presence of vortices, with respect to currents applied to either or both the superconductor and the ferromagnet within the heterostructure

    Experimental analysis of lateral impact on planar brittle material: spatial properties of the cracks

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    The breakup of glass and alumina plates due to planar impacts on one of their lateral sides is studied. Particular attention is given to investigating the spatial location of the cracks within the plates. Analysis based on a phenomenological model suggests that bifurcations along the cracks' paths are more likely to take place closer to the impact region than far away from it, i. e., the bifurcation probability seems to lower as the perpendicular distance from the impacted lateral in- creases. It is also found that many observables are not sensitive to the plate material used in this work, as long as the fragment multiplicities corresponding to the fragmentation of the plates are similar. This gives support to the universal properties of the fragmentation process reported in for- mer experiments. However, even under the just mentioned circumstances, some spatial observables are capable of distinguishing the material of which the plates are made and, therefore, it suggests that this universality should be carefully investigated

    Spin-polarized current and shot noise in the presence of spin flip in a quantum dot via nonequilibrium Green's functions

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    Using non-equilibrium Green functions we calculate the spin-polarized current and shot noise in a ferromagnet--quantum-dot--ferromagnet (FM-QD-FM) system. Both parallel (P) and antiparallel (AP) magnetic configurations are considered. Coulomb interaction and coherent spin-flip (similar to a transverse magnetic field) are taken into account within the dot. We find that the interplay between Coulomb interaction and spin accumulation in the dot can result in a bias-dependent current polarization \wp. In particular, \wp can be suppressed in the P alignment and enhanced in the AP case depending on the bias voltage. The coherent spin-flip can also result in a switch of the current polarization from the emitter to the collector lead. Interestingly, for a particular set of parameters it is possible to have a polarized current in the collector and an unpolarized current in the emitter lead. We also found a suppression of the Fano factor to values well below 0.5.Comment: Published version. 13 pages, 7 figure

    Vacinação, a importância das boas práticas e a prevenção de doenças de interesse em bovinocultura.

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    O objetivo de vacinar os animais é prevenir a ocorrência e a disseminação de doenças, mantendo-os saudáveis e minimizando os prejuízos econômicos. Os cuidados devem ser observados durante todo o processo, desde a aquisição, o transporte e a armazenagem, até a aplicação propriamente dita.bitstream/item/175356/1/Vacinacao-a-importancia-das-boas-praticas-e-a-prevencao.pd

    Produção e rendimento de óleo essencial de alecrim de tabuleiro em função da adubação orgânica.

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    Este trabalho objetivou avaliar a produção e o rendimento de óleo essencial em função da adubação orgânica em Lippia gracilis.Suplemento. Edição dos Anais do 52 Congresso Brasileiro de Olericultura, Salvador, jul. 2012

    Tamanho da amostra foliar para avaliação do estado nutricional e índice SPAD de capim-elefante irrigado para corte.

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    Resumo: compor a amostra promoverá a otimização da mão de obra, além de diminuir erros inerentes à recomendação e avaliação do estado nutricional. A coleta de folhas de forrageiras para a diagnose do estado nutricional é uma etapa importante para subsidiar a adubação, sendo o tamanho da amostra imprescindível para representar adequadamente a população de plantas a ser manejada. Assim, objetivou-se dimensionar o número de amostras de folhas para a diagnose do estado nutricional de capim-elefante irrigado para corte, bem como o índice de clorofila SPAD (Soil Plant Analysis Development). A avaliação foi realizada em capineira de capim-elefante, var. Cameroon, com irrigação fixa de baixa aspersão, em área localizada em Sobral-CE, em solo Neossolo fluvico. Coletaram-se 40 amostras simples, em zigue-zague, de maneira aleatória, escolhendo-se folhas recém-expandidas. As variáveis mensuradas foram os teores foliares de macro (N, P, K, Ca, Mg e S) e micronutrientes (B, Cu, Fe, Mn e Zn) e o índice indireto de clorofila, com auxílio de um clorofilômetro. Considerando aceitável um erro amostral de 10%, a coleta de amostras simples de 16 e 80 plantas, respectivamente, para macro e micronutrientes em capim-elefante seria adequada. Para a medida indireta da clorofila, 8 amostras são necessárias para obter um erro de 10%. [Leaf size sample to nutritional state and SPAD index evaluation in elephant grass irrigated under cuts management]. Abstract: The determination of the amount of sample units that will compose the sample express the optimization of the workforce, and reduce errors inherent in the report of recommendation and evaluation of nutritional status. The leaf collection for diagnosis of nutritional status is an important step, and the sample size necessary to adequately represent the population to be assessed. Thus, the objective was evaluation to the number simple design of leaf samples for the diagnosis of nutritional status of elephant grass irrigated for cutting and SPAD (Soil Plant Analysis Development) index. The study was conducted in elephant grass, with a low fixed sprinkler irrigation, in an area located in Sobral-CE in alluvial soil. It was collected 40 samples simple, randomly, choosing newly expanded leaves. The variables measured were foliar concentrations of macro (N, P, K, Ca, Mg and S) and micronutrients (B, Cu, Fe, Mn and Zn) and the indirect index of chlorophyll, using a chlorophyll meter. Considering an acceptable error of 10%, the collection of single samples of 16 and 80 plants, respectively, for macronutrients and micronutrients in elephant grass would be appropriate. For the indirect measurement of chlorophyll (SPAD index) 8 plants would be required to obtain a 10% error
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